微细电加工应用技术研究

微细电加工要达到工业应用的目的,需兼顾加工效率和加工精度两方面的要求.以微细孔、微细三维结构的加工为目标,进行了微细孔电火花加工、三维微细结构电火花伺服扫描加工及微细电化学加工技术的研究开发.设计出微细电极的损耗补偿进给和导向机构,开发出三维微细结构的电火花伺服扫描加工工艺,研究了采用阵列微细电极的微细电化学加工方法.微细孔电火花加工可连续加工直径小至100 μm的孔.伺服扫描电火花加工可便捷地在小于1 mm2区域内加工出三维微细结构.提出的微细电化学加工技术路线拟将微细电解加工应用于阵列微细孔和三维微细结构的加工.     

微细电火花加工的电极补偿方法研究

微细电火花加工中,电极损耗是引起加工误差的主要原因之一,因此必须进行电极的实时补偿以保证加工精度.研究了一种根据有效放电脉冲次数来进行实时补偿的方法,设计了基于可编程逻辑控制器(CPLD)的微细电火花补偿控制电路,并试验验证了此方法的可行性.     

微细电火花加工损耗补偿的研究

针对三维微细结构的微细电火花加工,应用等损耗理论,采用分层加工的方法,建立了单道单层加工时底面形状随电极损耗而变化的轮廓模型,在此基础上,提出电极损耗适时补偿的方法.实验测定了钨电极加工不锈钢的损耗率,应用适时补偿方法加工得到的单层单道窄槽的尺寸精度良好.     

喷油器流量控制阀板精密复杂微结构微细电火花加工技术

阐述了共轨喷油器流量控制阀板复杂微结构微细电火花加工解决方案,介绍了研制的三头数控微细电火花加工装备,分析了微细电火花铣电极损耗补偿及锥度沟槽、十字槽等加工工艺,总结出保证微细电火花铣削加工质量和效率的工艺规律。     

油泵油嘴复杂微结构微细电火花铣削加工试验

为解决油泵油嘴复杂微结构加工难题,开展了微细电火花铣削加工试验研究。在改进微细电火花加工机床系统的基础上,介绍了微细电火花铣削加工试验过程,并着重分析电极损耗补偿问题、加工效率问题的解决方法,进而完成油泵油嘴复杂微结构的精密微细电火花加工,总结出保证微细电火花铣削加工质量和加工效率的工艺规律。     

微细电极进给与激振机构及其微细孔电火花加工实验

研制了一种用于微细孔电火花加工的微细电极进给与激振机构,实现了加工过程中微细电极的伺服进给、损耗自动补偿、辅助激振及高精度导向。实验研究了加工过程中电极激振的频率对加工效率、加工孔径的影响。实验结果表明,电极激振振幅为0．6μm,频率位于4．3～4．5kHz范围内时,加工效率和所加工的微细孔尺寸精度同时明显提高。     

三维微结构微细电火花和电解组合加工实验研究

提出一种微三维结构的微细电火花和微细电化学组合加工工艺,利用三维伺服扫描微细电火花加工快速去除三维型腔材料和微细电解铣削加工形成高精度和高质量三维型腔轮廓表面的互补优势,实现三维微结构的高效率和高精度加工。该组合加工工艺可在同一台微细电加工装置上进行。以在四方体型腔内形成设计尺寸为400μm×400μm×180μm四棱柱结构的加工为例,实验加工出尺寸为410μm×406μm×181μm的四棱柱结构,加工材料的去除速度分别为微细电火花加工31 182μm3/s,微细电解加工11 017μm3/s,得到了加工效率和加工精度的优化组合。     

电极等损耗微细电火花加工技术

在综合国内外微细电火花加工技术最新发展的基础上 ,分析和研究了电极等损耗微细电火花加工技术的可行性 ,并进行了初步的理论探讨和实验研究。该方法可利用简单截面形状的电极和电极端面的轴向等损耗特性 ,实现三维高精度微细轮廓的电火花加工 ,具有重大的理论价值和良好的应用前景     

电火花铣削加工工艺与算法研究

介绍了电火花铣削加工工艺及其有关计算方法。在大量实验的基础上,研究了微细电火花分层铣削加工,采用电极底面放电方式、电极轨迹规划、电极的损耗及补偿策略和合理选择分层厚度及电极微进给量等关键技术,提高了加工精度和效率。     

微小回转结构微细电火花线切割加工工艺研究

在分析微细电火花线切割加工回转结构所需工艺条件的基础上,搭建了循环往复走丝微细电火花线切割回转结构加工系统,进行了方电极和微细金字塔阵列结构的微细电火花线切割加工基础实验。在加工过程中,根据切割厚度对微细金字塔阵列结构加工精度的影响,设计加工了阶梯型工件进行分析验证,总结了切割厚度对放电间隙补偿的影响规律。     

High Aspect Ratio and Complex Shaped Blind Micro Holes by Micro EDM

It is difficult to drill high aspect ratio through holes and complex shaped blind holes using micro EDM. The debris concentration in the narrow discharge gap causes abnormal discharges leading to excessive electrode wear and lower machining precision. In micro EDM, the electrode size is too small for internal flushing. This paper presents a new approach for effective self-flushing using planetary movement. Through micro holes with an aspect ratio of 18 have been drilled. This approach is also demonstrated by drilling blind noncircular micro holes with sharp corners and edges. The process performance characteristics are analyzed under different machining conditions.     

Servo scanning 3D micro-EDM based on macro/micro-dual-feed spindle

Using the end discharge of micro-rod-shaped electrode to scan layer by layer, micro-electrical discharge machining (EDM) can fabricate complex 3D micro-structures. During the machining process, the discharge state is broken frequently due to the wear of the tool electrode and the relative scanning motion. To keep a favorable discharge gap, the feed spindle of the tool electrode needs the characteristics of high-frequency response and high resolution. In this study, an experimental system with a macro/micro-dual-feed spindle was designed to improve the machining performance of servo scanning 3D micro-EDM (3D SSMEDM), which integrates an ultrasonic linear motor as the macro-drive and a piezoelectric (PZT) actuator as micro-feeding mechanism. Based on LabVIEW and Visual C++ software platform, a real-time control system was developed to control coordinately the dual-feed spindle to drive the tool electrode. The micro-feed motor controls the tool electrode to keep the favorable discharge gap, and the macro-drive motor realizes long working range by a macro/micro-feed conversion. The emphasis is paid on the process control of the 3D SSMEDM based on macro/micro-dual-feed spindle for higher machining accuracy and efficiency. A number of experiments were carried out to study the machining performance. According to the numerical control (NC) code, several typical 3D micro-structures have been machined on the P-doped silicon chips. Our study results show that the machining process is stable and the regular discharge ratio is higher. Based on our fundamental machining experiments, some better-machined effects have been gained as follows. By machining a micro-rectangle cavity (960 μm×660 μm), the machined depth error can be controlled within 2%, the XY dimensional error is within 1%, the surface roughness R_a reaches 0.37 μm, and the material removal rate is about 1.58×10⁴ μm³/s by using a tool electrode of Φ=100 μm in diameter. By machining multi-micro-triangle cavities (side length 700 μm), it is known that the machining repeatability error is <0.7%.     

微细电火花铣削电极运动轨迹加工工艺实验

在微三维结构微细电火花铣削过程中,电极运动轨迹的规划直接影响产品的加工效率和工具电极的损耗。针对钛合金微三维结构进行了不同铣削方式的加工工艺实验,选取了最佳电极运动轨迹,其加工时间和电极损耗均明显低于其他铣削方式。     

Gap control for near-dry EDM milling with lead angle

A new gap control strategy for five-axis milling using near-dry electrical discharge machining (EDM) has been experimentally investigated. The conventional EDM control strategy only allows the retraction of the electrode in the direction of machining trajectory, which results in inefficient gap control when the electrode is not perpendicular to the workpiece. The new gap controller is capable of retracting the electrode in the direction of its orientation. This enables more efficient enlargement of the discharge gap leading to faster recovery of average gap voltage. Experimental results show a 30% increase in material removal rate while the tool electrode wear ratio and surface roughness are not affected. Furthermore, EDM efficiency is improved due to the change in the electrode retraction in its axial direction. The gain tuning of the proposed controller is also discussed. This study shows the direction of electrode retraction is important for five-axis near-dry EDM milling.     

田口-灰关联法应用于Inconel 718微放电铣削参数最佳化(英文)

应用田口-灰关联法对Inconel 718微放电铣削多重质量特性如电极消耗率、材料去除率和扩口量进行最佳化,分析放电电流、脉冲时间、休止时间和极间间隙对加工Inconel 718之电极消耗率、材料去除率和扩口量的影响。实验结果表明,以最佳微放电铣削参数进行加工,其电极消耗率由5.6×10-9mm3/min降低到5.2×10-9mm3/min,材料去除率由0.47×10-8mm3/min增加到1.68×10-8mm3/min,扩口量由1.27μm降低到1.19μm。研究结果显示,应用田口-灰关联法,可以改善微放电铣削多重质量特性。     

Machining characteristics of magnetic force-assisted EDM

The gap conditions of electrical discharge machining (EDM) would significantly affect the stability of machining progress. Thus, the machining performance would be improved by expelling debris from the machining gap fast and easily. In this investigation, magnetic force was added to a conventional EDM machine to form a novel process of magnetic force-assisted EDM. The beneficial effects of this process were evaluated. The main machining parameters such as peak current and pulse duration were chosen to determine the effects on the machining characteristics in terms of material removal rate (MRR), electrode wear rate (EWR), and surface roughness. The surface integrity was also explored by a scanning electron microscope (SEM) to evaluate the effects of the magnetic force-assisted EDM. As the experimental results suggested that the magnetic force-assisted EDM facilitated the process stability. Moreover, a pertinent EDM process with high efficiency and high quality of machined surface could be accomplished to satisfy modern industrial applications.     

PZT激励同步压缩放电通道微细电火花加工工艺参数对加工结果的影响

提出了压电陶瓷(piezoelectric ceramic transducer,PZT)激励同步压缩放电通道微细电火花加工,目的在于改善微细电火花加工的放电环境。介绍了PZT激励同步压缩放电通道微细电火花加工原理,研究了开路电压、脉冲宽度、脉冲频率和峰值电流对其电极损耗和材料去除率的影响,并与不采用压缩通道方法的微细电火花加工进行了对比。结果表明:同等条件下,采用PZT激励同步压缩放电通道技术,提高了加工过程的稳定性和材料去除率,降低了电极损耗率,有效改善了放电环境。     

Improvement of Dry EDM Characteristics Using Piezoelectric Actuator

This paper describes improvement of the machining characteristics of dry electrical discharge machining (dry EDM) by controlling the discharge gap distance using a piezoelectric actuator. Dry EDM is a new process characterized by small tool electrode wear, negligible damage generated on the machined surface, and significantly high material removal rate especially when oxygen gas is used. However, the narrow discharge gap length compared with conventional EDM using oil as the dielectric working fluid results in frequent occurrence of short circuiting which lowers material removal rate. A piezoelectric actuator with high frequency response was thus introduced to help control gap length of the EDM machine. To elucidate the effects of the piezoelectric actuator, an EDM performance simulator was newly developed to evaluate the machining stability and material removal rate of dry EDM.     

Electrical discharge machining of Ti6Al4V with a bundled electrode

The aim of this study is to investigate an efficient Ti6Al4V electrical discharge machining (EDM) process with a bundled die-sinking electrode. The feasibility of machining Ti6Al4V with a bundled electrode was studied and its effect on EDM performance was compared experimentally using a solid die-sinking electrode. The simulation results explain the high performance of the EDM process with a bundled electrode by through the use of multi-hole inner flushing to efficiently remove molten material from the inter-electrode gap and through the improved ability to apply a higher peak current. A 3-factor, 3-level experimental design was used to study the relationships between 2 machining performance parameters (material removal rate: MRR, tool wear ratio: TWR) and 3 machining parameters (fluid flow rate, peak current and pulse duration). The main effects and influences of the 2-factor interactions of these parameters on the performances of the EDM process with the bundled electrode are discussed.